Bongofish

Hi all, just wanted to share a project I've been working on for a while and see what you guys make of it.

I'm trying to build a tiny computer that can be used as a digital sketchbook, note pad, laptop, retro gaming console, music player ....... Basically everything. I've already made two iterations of this thing but I keep getting new ideas as I go along so by the time I've finished one version it feels completely outdated compared to the version in my head.

The first version was this (http://sta.sh/0jo0c2iszy8) raspberry pi GameBoy DMG thing.

For some info on the second version see here (http://haikuo.deviantart.com/journal/DIGITAL-SKETCHBOOK-589604417)

And here's a little render I put together of what I'm trying to build right now.(http://img06.deviantart.net/d348/i/2016/121/c/5/concept_sketchbook_by_haikuo-da0l0io.png)

I added the Wacom pen in as well just to give it a little scale. Because of the massive push towards VR compatible hardware loads of new options have opened up when it comes to small DIY computers. When I first started this project I spent almost a year trying to find a suitable HDMI screen that was both small enough to be portable and high enough resolution to be good for art. I eventually found the Manga Screen (http://www.thing-printer.com/product/manga-screen/) which is what I used in version 2 of the DSB, it was only 800 by 480 res but it worked pretty well (I'd like to thank Elias Bakken for creating it, the only HDMI screens less than 5" before the Manga screen were found on very expensive Photography equipment and pretty bulky). But now you can find plenty of hardware manufactures starting to create light weight super high resolution ( 2k - 4k ) HDMI screens that are perfect for drawing with.

There has also been a massive improvement in single board computers (SBC) since I started this. With version one of the DSB I was using the first model B Raspberry Pi, which worked surprisingly well for retro game emulation but I was being optimistic if I thought I'd be using it for sketching. Now we have the Pi 3 which holds its own as a desktop computer and a massive variety of higher end options. Right now I'm planning on using a LattePanda (http://www.dfrobot.com/index.php?route=product/product&product_id=1404&search=lattepanda&description=true#.VyFUQEezmT8) board which can run a full Win 10 environment which means Photoshop and Steam although the Inforce 6540 (http://www.inforcecomputing.com/products/single-board-computers-sbc/qualcomm-snapdragon-805-inforce-6540-sbc) looks impressive too.

It's very clear to me that whatever hardware I choose it will be outdated within 3 months, so one thing I want to try and do with this device is make it as easy to upgrade as possible. I want to get away from the smart phone model where everything has a very limited shelf life and move towards something that could potentially exist for ever so long as I maintain it.

Right now I'm just collecting what I need to get started on DSB V3, I've also got uni exams so will probably not get started on the actual building of this for another month. I'd love to hear any ideas anyone has that I haven't thought of or suggestions.

I'll leave you with a little gif of the planed screen movement.(http://orig04.deviantart.net/b967/f/2016/118/9/9/1_by_haikuo-da0l0j7.gif)

I was thinking about getting my hands on a Pi3 but I just cant think of a good project at the moment.

My only thought about this project is the resolution of the screen. High DPI screens are excellent these days and I can understand why you would want to go that route for this project however, with the increase in pixel density for a reduced size screen comes less precision with the wacom pen, reason being that the pen tip has not reduced proportionally with the scaling of the screen, ie the area of the pens tip will cover many more pixels than it would on a regular monitor. This can obviously be compensated for by zooming in to an image to increase the relative size of a pixel, and perhaps for a sketchbook this is not an issue but I don't think you can expect to do any light and detailed work with this.

Also, will you be using a battery? What kind of battery will you use?

Those are my only thoughts on your project, and don't let them put you off as I'd really like to see you build this! Good luck!

Yeah Blender, how'd you know? I'm probably going to use Cherry MX switches since I'm more familiar with them. Really I shouldn't be using mechanical switches at all since they eat up so much space, it's just they look so good!

I didn't think of the effect of a high DPI screen on the precision of the graphics tablet. Right now I'm not even sure the lattepanda will be able to run at full 2K and might be limited to 1920 by 1080 which would make this a non issue. I'm going to use a XP-Pen G430 (https://www.amazon.co.uk/gp/product/B01BEWVOX4/ref=oh_aui_detailpage_o02_s00?ie=UTF8&psc=1) as the graphics tablet for this build, I tested it with a 4K screen and I didn't notice any precision issues. I had wanted something I could put behind the screen to make this a mini Cintiq but I couldn't find anything which would match the dimensions so I'll probably have the tablet on the opposite side to the keyboard which is why I need the screen to rotate. If any of you know of a tiny graphics tablet that would fit this (http://www.topfoison.com/product/New-development-5.98-inch-2K-lcd-display-with-HDMI-board.html) screen I'd love to hear about it.

For the battery I'm going to try and lobotomise one of these (https://www.amazon.co.uk/gp/product/B00UC3J8DU/ref=ya_st_dp_summary) so that it fits in a portable case. That way I can power the screen from the 1A usb output and power the SBC from the 2A output. An issue I had with V2 was there wasn't enough current to power everything from the SBC so things got a little dodgy.

Battery arrived yesterday and it looks like it will work out. Pineng really don't want people getting into their products though, had to carve my way in with a knife and slowly prise the top off without damaging anything inside. I've had to do something similar with another of their power banks before, wish they just used screws.

Before (http://orig10.deviantart.net/0dd8/f/2016/121/5/9/untitled_by_haikuo-da0v8y4.png)

It should fit fine, I can always extend the wires attaching the lipolys to their pcb if I need to move things around. I love the little battery indicator, it looks great in the dark and should be genuinely useful for working out how much charge is left. There's even an LED flash light mode which I'll have to incorporate somehow.(http://img01.deviantart.net/03b8/i/2016/121/8/1/untitled_by_haikuo-da0v8z1.png)

Also started tearing down the XP-pen tablet, it's incredibly thin so should work pretty well. I wish there was a tablet with less excess space around the actual active drawing area, I checked under the cover surface and it looks like the pcb tracks go right up to the edge so I wont be able to cut anything away from the edges. This tablet should be the largest component of the build and is what is determining the footprint of the device, if there was something smaller I could make the whole thing smaller.(http://img09.deviantart.net/3b30/i/2016/121/0/b/untitled_by_haikuo-da0v8xk.png)

Ok it's been ages since I've updated here, mostly because of exams but also stuff takes ages to arrive. Luckily this should be a fairly big update covering the progress I've made to make up for the silence.

Finally decided, bought and torn down the mini pc I'm planning to use. It's an Intel Skull Canyon Nuc with an Intel® Core™ i7-6770HQ processor with Intel® Iris™ Pro graphics. First some pics then I'll get into why I chose it.

I'd looked at this NUC a while ago but had discounted it based on the width of the case, at the time it still hadn't been released and it looked a little too wide for a hand-held device. However thanks to a teardown on tweaktown.com I could see that much off the width was actually the fan and heatsink and the board itself is only about 14cm by 11cm so should work fine. I decided this would be the perfect motherboard for the DSB because it has no problem running programs like Photoshop or even Blender so I wouldn't need to find alternative software and change my workflow. Plus it should be able to run games pretty well given Intel is primarily marketing it as a gaming mini pc. Apparently you can hook it up to the new external GPUs that are starting to show up and use it for VR and rendering but I'm sceptical how well that works right now.

I'm going to have to do a bit of work hacking together a new heatsink that comes directly out the back on top of the CPU instead of to the side. I'll probably leave a hole in the case just to give as much airflow as possible over the heatsink since the better the passive cooling is, the less the fan will have to be on draining the battery. Plus, I think a nicely designed copper heatsink could look pretty good.

The Nuc is supposed to run off a 19V, 120W AC-DC power adapter which bascially means the batteries I was planning to use aren't going to work. But I've got a new external battery, 40,000 mah this time and capable of powering anything from 12V to 21V. I've tested it out already and it seems to work perfectly, I was worried it wouldn't be able to supply a high enough current to power the Nuc when gaming but it seams to be fine.

The Nuc also has another advantage over the other boards I've been looking at which is that it can run displays with resolutions higher than 1920 by 1080. Given that the screen I'm planning on using has a 1440×2560 native resolution this works out well. The screen I've chosen to use is a 5.98 inch 2K LCD HDMI display made by Topfoison (http://www.topfoison.com/product/New-development-5.98-inch-2K-lcd-display-with-HDMI-board.html), it's designed for use with VR but works well as a normal monitor as well.

One thing I'm thinking of looking into is getting some polarising film to reduce reflections for when I'm using it outside. I remember how my gameboy colour became virtually unusable in direct sunlight and while I know the screens are completely different even with indoor use I can see reflections could be an issue with this screen.

Done some work on the heatsink and the keyboard, last thing left to do now is finish designing the case which is taking way longer than I thought it would. I keep changing my mind how I want the two halves of the device to connect, I can't just design a hinge like a normal laptop since the screen needs to rotate so I can use it with the tablet on the back of the keyboard.

Haven't got any photos of the new heatsink right now so keyboard update first:The plan for the keyboard was to have as many mechanical keys as I could comfortably fit plus two "joystick" keys and two more keys on the back to act as triggers. The joysticks and triggers were so it would feel more like a hand held device than strictly just a laptop. I've ended up going with Cherry MX brown switches and two 5 way joystick switches.

The base plate is lazer cut from aluminium and has the special feature of only letting you insert keys in sideways since I messed up on the template.

Fortunately nothing went horribly wrong when putting everything together, just a few dead diodes and loose connections which were fairly easy to fix. With hindsight I should have used single core wire for everything, would have made things a little easier. Here's an image of what everything looks like connected up to the Teensy.

Theres lots of unconnected wires coming from the Teensy just incase I decide to add LEDs later on. I wouldn't be able to get to the pins on the under side of the board without desoldering a bunch of stuff otherwise.

Most of the custom keyboards I've seen build logs for ended up using something like TMK for the firmware to make their keyboards actualy work. I decided to program the Teensy from scratch partly becuase I wanted to figure it out myself and partly becuase my keyboard has joysticks which would have been tricky to work into TMK. It was easy to get single keypresses working, slightly harder with multiple keypresses along with modifier keys, but in the end it sorted itself out and I've now got a fully working keyboard.

I made sure to work keymaps and macros into the firmware so I can change the layout of the keyboard on demand and run scripts. Should make the tiny keyboard a little more usable given it's size.

Micro-laptop with guts hanging on standardized connectors, this is brilliant! I was pondering something similar, but a bit bigger - ended up sourcing a ThinkPad X61 tablet screen @ 1400x1050, 12 inches. The digitizer is built in, so it has about 3mm bezel on each side. Was still on the cliff regarding hardware, I started carving a mITX board for that, since that's the smallest thing I found at the time that still carried enough processing power for actual work.

Big thumbs up for not optimizing this for thinness. That's a load of a sandwich ;DSomehow reminds me of the Vaio's ventures into ultraportables, the VGN-UX and Vaio P.

Any idea if that Nuc supports some kind of graphics cards? eGPU or something?

Did you measure the battery times?

Did you choose the hinge yet? Are you gonna design it yourself, or source from existing parts?Fujitsu convertibles have those hinges you can twist both sides... T902 up, but the more recent ones are quite wide, may break your dimensions.

Check Camineet's game controller build thread on Geekhack, he was hacking in two joysticks into a teensy, there are code snippets there to get it running. And the whole thread is an awesome study into ergonomics.

Thanks for the thoughts Sinusoid! Camineet's game controller thread was a good read. Make sure to send me a link to your build if you make a build log for it, would be interesting to see how you solve similar problems to the ones I'm running into.

The Skull canyon does support external graphics cards (as you found out) but they're above and beyond what I need from a portable device right now so I doubt I'll be incorporating one into this build. If I end up needing more performance at home I reckon it'd be more sensible just to get an actual desktop computer. But if I get a chance to try one out for free I'd be all for it :)

You can roughly see the hinge in the above renders I'll try do a close up of them in a bit to show how they'll work. I was looking at hinges similar to the T902 at the beginning but a hinge like that wouldn't have fit properly unless I wanted to block some of the NUC's ports and it would have been a massive pain making it so both halves could close together as well as rotate.

Haven't had a chance to formally measure battery life yet. I did run the NUC off battery for a few hours when I was trying to troubleshoot some problems and it only fell by about 20%. However I didn't want to measure battery life then because that was before I had the keyboard working along with other peripherals that are going to drain the power further. Plus I suspect the NUC will run a little hotter once its in the case and I'm not sure how effective my hand made heatsink + fan combo is yet so I'm waiting to get everything together before I do a proper battery life check.

A few things are wrong with it right now, the Nuc doesn't quite line up with the ports and (about 2mm) and the bottom was supposed to have a hole for the acrylic screen for the tablet. Should be quite easy to fix both of problems with a dremel and a bit of sandpaper though. Was genuinely surprised I got off so lightly seeing as I had to finish most of the modelling on holiday where I couldn't measure anything.

The Blue LEDs of the battery indicator look so nice shining through the case. Also, keycaps arrived a while ago. Was a massive pain finding clear acrylic ones but the slightly clinical look they give it was worth it.

Really want to get this finished before I go back to uni but I keep getting more ideas for it. I could add a pico transducer to the teensy and code it up so one of the keymaps works as a tiny 1bit piano. Still got to work what to cover the joy sticks with. I was trying to see how I could modify some of the leftover keycaps so they would fit but I'm not sure it'll work. Also tempted to get a M.2 to msata adapter so I can stick in the 1tb mstat drive I used for v2 of the DSB for some extra storage. Plus I could still add LEDs to the keys, not sure if I have enough pins left on the teensy to control all of them directly but someone was telling me I could use a PWM shift register to do a similar thing.

The case has been sanded, primed and spray painted white with a clear coat over the top. Messed up the spay painting a little in some places, I think I'd probably just go for a clear coat next time. Also made a hole in the side of the case so the NUC can actually fit properly. It doesn't look too bad but I'll probably end up covering it with a sticker or something.

I also messed up by spray painting over the battery indicator, I thought the light would still pass through the paint but no. I had to spend ages sanding that area of the case just to get the light coming through again, another reason I'd skip painting the case if I did it again.

I decided not to try and cut a whole for the graphics tablet, I just don't have the right tools to properly cut a straight line through plastic and I didn't want it looking messy. The tablet still worked without the hole so it was fine.

I tried a cheap M.2 sata to msata converter but it was too wide and wouldn't fit, it should still be possible to use my msata ssd but I'd need a converter which uses a cable and I didn't have time to order one.

After painting I added all the nuts with super glue (this was less easy than it sounds) and magnets which would give the bolts a nice magnetic attraction making them less likely to fall out when not nutted in.

Getting everything into the case was a massive hassle, managed to break the battery and the tablet when installing them. luckily I managed to fix the battery with some soldering (there was still a capacitor which didn't appear to be properly soldered to the board, but it was like that when I took it out of the case so I just left it) but by the time I realised the tablet was dead everything was glue gunned in. I could have used a hair dryer to melt the glue and taken everything out again but by that point was I almost out of time and didn't want to risk breaking the battery again.

One good thing which came of this was after I realised the tablet was broken I decided to dig out my super old Wacom bamboo one tablet which had broken this time last year and attempt to fix it. Turns out it was only the cable which had broken and not the pcb so after replacing the cable it worked again.

Getting everything into the top of the device was even harder than the bottom, but luckily nothing broke this time. I added the display and acrylic screen then found out they were sticking together and creating this horrible 'bubble' effect on the display. So I had to add two strips of acrylic above and bellow the screen to prise them apart and remove the bubble as well as mount the acrylic screen on 4 washers to add more separation. After that came the displays pcb plus all the cabled that come off it. This is the part which really took ages, I had to bend a 1 meter hdmi cable into a tiny case over and over just to get it to fit. If I had been able to get the NUC to work with a shorter cable things would have been much easier.

I also had to completely redo the heatsink to get the fan to fit, coerce a display port to hdmi adapter to bend in ways it was never designed for, curl the power cable so it takes up less space and add switches so that I can tun off the display and whatever else I end up adding.Also scavenged some rubber feet off the Skull Canyon case so it doesn't slip around and added some capped nuts to the joysticks to give them a pretty cool utilitarian feel.

And that's about where I am now.I've made a device which is basically a 1/4 sized laptop (albeit much thicker) with a mechanical keyboard, and an in built graphics tablet (which is currently broken). I'm back at uni now so can't do any more till Christmas but I've been using it for the past few days with my revived bamboo one tablet and it works pretty well.

[...]Getting everything into the case was a massive hassle, managed to break the battery and the tablet when installing them. luckily I managed to fix the battery with some soldering (there was still a capacitor which didn't appear to be properly soldered to the board, but it was like that when I took it out of the case so I just left it) but by the time I realised the tablet was dead everything was glue gunned in. I could have used a hair dryer to melt the glue and taken everything out again but by that point was I almost out of time and didn't want to risk breaking the battery again. [...]

What You mean by writing dead tablet? If it doesn't work at all, check cable. It may be broken. If it's visible to system but doesn't see pen, try to remove battery. Big metal part (battery) under digitizer surface may cause interference with the digitizer. BTW, I prefer to use hot melt glue. It's not as esthetic as super glue, but much easier to remove. Just put some drops of acetone or alcohol at end of junction and wait minute. Hot glue will fall of without using force.

So originally I was planning on having a big sheet of metal behind the digitizer to hold it in place, I quickly found out this caused massive interference and scrapped the idea. I made sure to test the tablet inside the case with the battery behind it and it didn't cause any interference at the time so I don't think its that. Basically when I plugged in the tablet no lights came on or anything. I'm pretty sure what's happened is one of the wires in the usb cable must have broken off the tablet's pcb when I squeezed the battery in the case. It would be a pretty easy fix except I'd need to disassemble everything to be able to get at it. Right now I don't even have access to a soldering iron so I wont be able to do anything anyway until I get back from uni.

I made sure to use hot glue for anything that I might need to redo later on for the reason you say. Super glue was really just for things like the nuts and magnets which I'd never need to remove.

Yeah so the HDMI cable caused me so many problems. I was hoping to use a tiny HDMI ribbon cable but as much as I'd like to say every HDMI cable is them same when it comes to the NUC this just isn't the case. Heres a link to a thread I started on the intel forums to try and get a fix:https://communities.intel.com/thread/103047 (https://communities.intel.com/thread/103047)

Never really narrowed down what the problem was, I think the Intel guys never expected someone to want to use a HDMI cable less than 30cm long so there were interference issues or something. The problem may well have been resolved now but I'm not taking it apart to find out.

Yeah so that's part of the original heatsink that came with the board. It originally has some heat pipes coming off it to a fan at the side of the nuc but seeing as this would have been too wide for my case I removed the pipes put two heatsink blocks on top and the fan right next to it. I don't get any heat problems so it seems to work.

Sorry man I really should have taken more pictures as I went along, it's just when I get started I forget to stop and document the process :)While there's still more I can add to it it's realistically not going to get an upgrade for a long time as it's reached the "good enough" threshold for me.